1. Field of the Invention
This invention relates to magneto-optical disc recording/reproducing devices and, more particularly, to a magneto-optical recording/reproducing device which detects an incorrect type of disc loaded into it and, responsive thereto, prohibits a recording/reproduction operation.
Some conventional magneto-optical disc devices are capable of recording compressed audio data on a compact magneto-optical disc utilizing thermal magnetic recording.
As shown in FIG. 1, in such a prior art magneto-optical disc device 1, an audio signal AI is inputted successively and is converted into digital signal at an analog-to-digital converter (A/D) 2.
The converted digital signal is audio compression processed at an audio compandor 3 (to decrease the quantity of data) to form audio data DAI.
The magneto-optical disc device I stores this audio data DAI in a memory circuit 5, through a memory controller 4, and outputs the audio data DAI successively to a data processing circuit 6.
The data processing circuit 6 divides the audio data to be outputted successively from a memory circuit 7 into prescribed blocks and forms error correction codes. Then, the data processing circuit 6 modulates the data with a modulation method suitable for magneto-optical disc recording to form recording data, and outputs the resultant recording data to a magnetic head driving circuit 8.
The magneto-optical disc device I controls the overall operations with a system control circuit 11, to rotate a magneto-optical disc 10 at a prescribed revolution speed via a servo circuit 12.
Furthermore, the magneto-optical disc device 1 drives a thread unit 13 via the servo circuit 12 and thus, transfers a magnetic head 9 signal and an optical head 14 signal to prescribed recording tracks of the magneto-optical disc 10.
The magneto-optical disc device 1 drives the magnetic head 9 corresponding to the recording data and impresses the modulation magnetic field formed by the magnetic head 9 to a desired recording track of the magneto-optical disc 10.
Under these conditions, in the magneto-optical disc device 1, an optical beam is irradiated from the optical head 14 to the part of the disc impressed with the modulation magnetic field and thus, by applying the method of thermal magnetic recording, audio data is recorded with high density.
Furthermore, the magneto-optical disc device 1 detects the reflection light of this optical beam at the optical head 14 and outputs the detection result to an address decoder 16 via an amplifier 15 and, thus, detects the address information which was previously recorded on each track.
Wobbling pre-groove is also pre-recorded on the disc. This wobbling is FM modulated so as to record the address information into the whole disc.
Thus, in the magneto-optical disc device 1, audio data can be recorded successively on desired recording tracks depending upon this detection result of position information.
Furthermore, at this point, in the magneto-optical disc device 1, tracking error signal, focus error signal, etc., from the optical head 14 are reproduced at the amplifier 15 and are outputted to the servo circuit 12. Thus, the desired audio data can be certainly recorded.
At the time of this recording, in the magneto-optical disc device 1, by processing audio data per block at the data processing circuit 6, as shown in FIGS. 2A and 2B, audio data will be recorded per cluster (FIG. 2A).
One cluster is composed of the sub data for 4 sectors and the main data of 32 sectors (FIG. 2B).
When a track jump is detected based on the position information detection result, the magneto-optical disc device 1 stops recording, returning to the former recording track and starts recording audio data from the recording track on which the track jump occurred.
At this point, the magneto-optical disc device 1 again outputs audio data stored in the memory circuit 5 per cluster and thus, the dropout of audio data can be avoided by utilizing the memory circuit 5 as a buffer memory. Even in the case where the entire magneto-optical disc device 1 failed to write data due to vibrating, etc., audio signals can be recorded successively.
On the other hand, during reproduction, the magneto-optical disc device 1 decreases the quantity of light of optical beam to be outputted from the optical head 14, as compared to during recording. By detecting changes of polarized wave plane of reflection light obtained from the magneto-optical disc 10, the magneto-optical disc device reproduces the recording data of magneto-optical disc 10 by utilizing the Kerr effect.
The magneto-optical disc device 1 demodulates the output signal of the amplifier 15 at the data processing circuit 6 and processes error correction, then outputs the demodulated, error-corrected, data to the memory controller 4.
At this point, the magneto-optical disc device 1 outputs the audio data SDO reproduced by utilizing the memory circuit 5 as the buffer memory in the same manner as when recording. The audio compandor 3 audio expands the data.
With this arrangement, the magneto-optical disc device 1 demodulates the audio data SDO to digital audio signal AO at this audio compandor 3 and outputs in the form of analog signal via a digital-to-analog converter 16.
Furthermore, during reproduction, by monitoring sub data, which are added to the main data, the magneto-optical disc device 1 detects the track jump. Audio data will be repeatedly reproduced per cluster from the same track based on this detection result as occasion demands. Thus, even if track jump occurs during reproduction, audio signals can be reproduced avoiding the sound cut in advance.
This type of magneto-optical disc recording/reproducing device is disclosed, for example, in U.S. Pat. No. 5,224,087.
Hereupon, it is considered to be convenient if this type of magneto-optical disc device can be used as an external memory device for storing, e.g., computer data.
In this type of magneto-optical disc device, since data can be accessed randomly, the access time can be shortened.
Also since the memory capacity of magneto-optical discs is large, and they are developed already for audio, the magneto-optical disc itself can be produced easily and in large quantities, and can be supplied at lower cost than the conventional disc.
Also, since the magneto-optical disc can be removed, like floppy discs, it is considered that its usability can be improved, as compared with the hard disc.
However, a magneto-optical disc with recorded audio data may be erroneously loaded onto a magneto-optical disc device for data recording. Conversely, a magneto-optical disc for data recording may be erroneously loaded onto a the magneto-optical disc device for audio reproduction.
Accordingly, if the magneto-optical disc device for audio reproduction is allowed to be used as a data recorder, it has been a problem that the user must be careful as to which particular type of disc device he inserts.
2. Object and Summary of the Invention
In view of the foregoing, an object of this invention is to provide a magneto-optical disc device which is capable of simplifying control of the magneto-optical disc device, even when a magneto-optical disc inserted into the disc device is for recording.
The foregoing object and other objects of this invention have been achieved by provision of a device for recording/reproducing audio data and program data which comprises: an input/output section for audio data; an input/output section for program data; a compandor for extension processing audio data in which the inputted audio data to be connected to the input/output section for audio data is compressed to output; a switching circuit for switching the compandor with input/output section for program data; a discrimination circuit for judging whether the loaded recording medium is for audio or for program; a control section for controlling the switching circuit based on the result of the discrimination circuit.
Further, this invention provides a recording/reproducing device for audio which comprises a judgment section for judging the loaded recording medium, and a control section for controlling the prohibition of recording/reproducing operation when the judgment section judges that the recording medium for data storage is loaded.
Furthermore, this invention provides a recording/reproducing device for data storage which comprises judgment section for judging the loaded recording medium, and a control section for controlling the prohibition of recording/reproducing operation when the judgment section judges that the recording medium for audio is loaded.
The nature, principle and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings in which like parts are designated by like reference numerals or characters.